Field computations through the ACA algorithm

The adaptive cross approximation algorithm is invoked for the fast construction of the method-of-moment matrix involving source basis functions for the currents and a set of auxiliary test functions that samples the radiated electromagnetic (EM) field. Once the adaptive cross approximation coupling matrix is constructed, the far and near fields from a source current are obtained directly through a single matrix-vector product. The post-processing method is particularly fast when the EM fields are smoothly varying over their sampling domain, or when far fields need to be computed for many current distributions, e.g., for sets of macro basis functions arising in several domain decomposition methods.